A representative for Claire Danes has threatened to sue a U.S. newspaper over false reports the actress has experienced permanent skin darkening around her eyes after endorsing an eyelash growth treatment.

Danes joined Brooke Shields this summer as a celebrity spokesperson for Latisse, a treatment from the makers of anti-aging facial injections Botox.

Latisse bosses warn that skin darkening is a reversible and less-common side effect of using the product.

The actress documented her 16-week journey with the cosmetic in a video diary on the Latisse website, admitting she suffered redness around her eyes for "about a week" at first, but hadn't experienced any side effects since.

A spokesperson for Latisse confirmed company bosses had no knowledge of Danes' alleged side effect: "We can only speak to what Claire has shared with us regarding her experience with Latisse, which is that she has been pleased with her results and continues to use the product.

"Claire's team has shared with us that she has not experienced skin hyperpigmentation following use of Latisse."